/**************************************************************************
 *									  *
 *		 Copyright (C) 1994, Silicon Graphics, Inc.		  *
 *									  *
 *  These coded instructions, statements, and computer programs  contain  *
 *  unpublished  proprietary  information of Silicon Graphics, Inc., and  *
 *  are protected by Federal copyright law.  They  may  not be disclosed  *
 *  to  third  parties  or copied or duplicated in any form, in whole or  *
 *  in part, without the prior written consent of Silicon Graphics, Inc.  *
 *									  *
 **************************************************************************/

#include "guint.h"
#include <ultratypes.h>

void guPerspectiveF(float mf[4][4], u16 *perspNorm, float fovy, float aspect, float near, float far, float scale)
{
	float	cot;
	int	i, j;

	guMtxIdentF(mf);

	fovy *= 3.1415926 / 180.0;
	cot = cosf (fovy/2) / sinf (fovy/2);

	mf[0][0] = cot / aspect;
	mf[1][1] = cot;
	mf[2][2] = (near + far) / (near - far);
	mf[2][3] = -1;
	mf[3][2] = (2 * near * far) / (near - far);
	mf[3][3] = 0;

	for (i=0; i<4; i++)
	    for (j=0; j<4; j++)
		mf[i][j] *= scale;

	if (perspNorm != (u16 *) NULL) {
	    if (near+far<=2.0) {
		*perspNorm = (u16) 0xFFFF;
	    } else  {
		*perspNorm = (u16) ((2.0*65536.0)/(near+far));
		if (*perspNorm<=0) 
		    *perspNorm = (u16) 0x0001;
	    }
	}
}

void guPerspective(Mtx *m, u16 *perspNorm, float fovy, float aspect, float near, float far, float scale)
{
	Matrix	mf;

	guPerspectiveF(mf, perspNorm, fovy, aspect, near, far, scale);

	guMtxF2L(mf, m);
}